Vehicle safety standards have evolved in an effort to provide safer passenger cars. A vehicle safety standard for roof crush resistance is FMVSS No. 216. The loading requirements of FMVSS No. 216 have been increased with the objective of providing greater protection for passengers in vehicle rollover events. The standard will require that vehicles meet a roof strength requirement of 3.0 times the vehicle weight. This requirement increase poses a significant challenge to vehicle manufacturers. Increased roof strength requirements must be met while also achieving increased fuel economy that may demand lighter weight and less structure.
Large passenger vehicles often have three or more sets of vertical pillars supporting a roof structure. Pillars are typically referred to from front to rear, as A, B, and C-pillars. Some vehicles also employ a fourth, D-pillar. In contrast, some small vehicles with only one row of doors have only two pillars. Vehicles with front and rear side doors generally have a middle B-pillar. The B-pillar defines the separation between separate front and rear door openings. Existing roof structures rely substantially on a mid-vehicle vertical B-pillar, to sustain vertical roof crush loads. The size of the pillar required to meet roof crush requirements may obstruct access to the vehicle by occupants. It generally restricts the space available for door openings, and therefore the ease of entry and exit by occupants of the vehicle. The B-pillar also limits the size of objects that are capable of being loaded through the door openings. The B-pillar may also obstruct the driver's field of view. The B-Pillar also presents vehicle styling limitations, since its placement is often dictated by functional requirements. It would be advantageous to design a vehicle body with no B-pillar, offering several customer space advantages, yet still meeting increased roof strength requirements.